1. Field of the Invention
The invention relates to a disk brake having a brake disk. a friction brake lining and an actuating device for pressing the lining against the disc.
2. Description of the Prior Art
Disk brakes, are known per se, have both a brake disk and typically two friction brake linings disposed one on each side of the brake disk. The friction brake linings are received in a brake caliper. Most disk brakes used today are actuated hydraulically; that is, for generating a braking moment, the friction brake linings are pressed hydraulically against the brake disk. It is possible for each friction brake lining to be pressed by a hydraulic piston assigned to it against the brake disk. It is equally possible for one of the friction brake linings to be pressed hydraulically against the brake disk and for the other friction brake lining, by a reaction force transmitted via the brake caliper, to be pressed against the other side of the brake disk. In that case, the brake caliper is embodied as a floating caliper that is displaceable transversely to the brake disk.
It has also been proposed that disk brakes be actuated electromechanically. In this connection, see International Patent Disclosure WO 96/03301, for example. The actuating force for pressing the one friction brake lining against the brake disk is exerted against the friction brake lining in this case by an electric motor via a rotation/translation conversion gear, such as a spindle drive. However, electromechanical disk brakes have the disadvantage that to generate a sufficiently high tightening force (this is the force with which the friction brake lining is pressed against the brake disk) and for fast tightening and release, that is, to attain sufficiently high dynamics, a large and consequently heavy electric motor is needed. This is undesired, since the disk brake can be only poorly accommodated in the interior of a vehicle wheel rim, where it is usually placed. Moreover, the disk brake is typically mounted on a wheel carrier and forms an unsprung mass. A high weight of the unsprung mass adversely affects a vehicle's road holding ability and is therefore unwanted. Another disadvantage of known electromechanical disk brakes is their high power consumption, which puts a considerable burden on an on-board electrical system of a motor vehicle.